Acoustic transmission device and process for tracking selected hosts

ABSTRACT

A new acoustic tag and process are disclosed for identifying and tracking underwater hosts in up to three dimensions. The acoustic tag has an operation lifetime up to a year or longer at a pulse rate interval of about 15 seconds. The acoustic tag has a signal detection range up to at least about 500 meters that enhances detection probability.

STATEMENT REGARDING RIGHTS TO INVENTION MADE UNDER FEDERALLY-SPONSOREDRESEARCH AND DEVELOPMENT

This invention was made with Government support under ContractDE-AC05-76RLO1830 awarded by the U.S. Department of Energy. TheGovernment has certain rights in the invention.

FIELD OF THE INVENTION

The present invention relates generally to acoustic tracking devices andsystems. More particularly, the present invention relates to attachableacoustic transmission devices for detection and remote tracking ofsmaller hosts both inanimate and animate in up to three dimensions inreal-time or as a function of time.

BACKGROUND OF THE INVENTION

Acoustic telemetry involves acoustic devices (or tags) commonly used tomonitor behavior of fish. Acoustic tags transmit a sound signal thattransmits identification, location, and other information about a taggedfish to a receiver at a selected pulse rate interval (PRI), or “ping”rate. The receiver detects signals emitted by the acoustic tag andconverts the sound signals into digital data. Post-processing softwarethen processes the digital data and provides location information aboutthe tag and thus the behavior of the fish when the receiver detects thesound signal. By identifying the signature of the acoustic signal aspecific animal may be identified, which allows tracking the behavior ofthe host. Acoustic data may be used, e.g., to estimate survival of fishthrough dams and other routes of passage. However, conventionaltransmitters are too large for small hosts (30-100 g mass and 180-270 mmlength), have short lifetimes, and/or have an inadequate transmissionrange that to date have precluded intensive research of small hosts suchas juvenile sturgeon using acoustic telemetry techniques. Recently, aninjectable acoustic tag was developed for the U.S. Army Corps ofEngineers for tracking juvenile salmon detailed in U.S. patentapplication Ser. No. 14/014,035 filed 29 Aug. 2013, and other acoustictags for tracking other small hosts detailed in Patent Application No.:PCT/US14/53578 filed 29 Aug. 2014, which references are incorporatedherein in their entirety. The injectable acoustic tag works well fortracking yearling Chinook salmon in river systems. However, it is notoptimal for long-term monitoring of hosts requiring a stronger acousticsignal and longer service life including, e.g., juvenile (<1 year old)sturgeon. Accordingly, new tag designs are needed that reduce theoverall size, mass, and/or volume, that enhance the power sourcevoltage, tag lifetimes, and transmission range, and reduce adverseeffects and costs associated with attachment (which includesimplantation) thus broadening the range of potential applicationsincluding, e.g., investigating behavior and habitat of juvenile sturgeonand other small species. The present invention addresses these needs.

SUMMARY OF THE INVENTION

The present invention includes a new acoustic transmission device(acoustic tag) and a process for remotely tracking various hosts in upto three dimensions in real-time or as a function of time. The acoustictag may include a power source that delivers a power source voltage topower a tag circuit. The tag circuit may deliver a selected voltage to apiezoelectric transducer (PZT) that transmits an acoustic transmissionsignal at a signal intensity selected between about 159 dB and about 163dB. The tag may be configured to provide a selectable tag lifetime atthe selected signal intensity of at least about 98 days at a pulse rateinterval of about 5 seconds.

The present invention also includes a method for tracking selectedhosts. The method may include delivering a selected voltage from a tagcircuit powered by a power source to PZT in the acoustic transmission(tag) device. The tag device may be attached to the selected host. Thetag circuit may generate an acoustic transmission signal in the PZT at aselected signal intensity over a selectable tag lifetime. Signalintensity may be selected between about 159 dB and about 163 dB.

In some embodiments, the tag lifetime may be at least about 365 days ata transmission (ping) rate of about 15 seconds at a signal intensity of161 dB.

In some embodiments, the tag lifetime may be at least about 249 days ata transmission (ping) rate of 10 seconds at a signal intensity of 161dB.

In some embodiments, the tag lifetime may be about 156 days at a pulserate interval of about 5 seconds and an acoustic signal intensity of 159dB.

In some embodiments, the acoustic tag may include a power source thatdelivers a selectable power source voltage that powers components of theacoustic tag located on, or coupled to, a tag circuit. In variousembodiments, the power source voltage may be selected between about 1.8V and about 3.0 V.

In some embodiments, the tag circuit may include a dual boost convertersub-circuit that couples to two analog switches. In some embodiments,one of the analog switches may be coupled to the PZT through aninductor. The other analog switch may be coupled directly to the PZT.This configuration allows a higher peak-to-peak voltage from the tagcircuit to be delivered across the PZT than would normally be deliveredto the PZT. In some embodiments, the two analog switches may be directlycoupled to the PZT, which permits the voltage from the tag circuit to bedirectly applied to the PZT.

In some embodiments, the dual boost converter sub-circuit may transformthe voltage delivered from the power source into two output voltages.One output voltage may be a higher voltage (e.g., about +7 volts) thanthe power source voltage. The other output voltage may be a lowervoltage (e.g., about −3 volts) than the power source voltage. The dualboost converter sub-circuit may share a single inductor to reduce thesize of the tag.

The dual boost converter sub-circuit may alternately switch between thetwo voltage potentials in succession and deliver the two voltagesthrough the respective analog switches to generate a selectable outputvoltage from the tag circuit to the PZT that drives transmission of theacoustic signal from the acoustic tag. In the exemplary embodiment, whenthe two voltage potentials delivered by the dual boost convertersub-circuit alternate between about +7 volts and about −3 volts, thevoltage delivered from the tag circuit to the PZT may be about 20 volts(peak-to-peak).

The method may include delivering the selected (drive) voltage from thetag circuit from a boost conversion sub-circuit within the tag circuitacross an inductor to the PZT.

In some embodiments, the energy expenditure for transmission of theacoustic signal from the piezoelectric transducer may be less than orequal to about 385 μJ per transmission at a signal intensity of 163 dB.

In some embodiments, the energy expenditure for transmission of theacoustic signal from the piezoelectric transducer may be less than orequal to about 283 μJ per transmission at a signal intensity of 161 dB.

In some embodiments, the acoustic signal may include a transmissionrange of at least about 500 meters at full intensity.

In some embodiments, the new acoustic device (tag) may include a lengthat or below about 24.2 mm, a diameter at or below about 5.0 mm, and adry weight of less than about 0.72 grams.

The method may include attaching the acoustic tag to the selected hostat a selected location.

The acoustic signal may be encoded with one or more tag codes of aselected code length. The acoustic signal may contain location data,identification data about the host, and/or sensor data that may all betransmitted from the acoustic tag to a receiver located external to thehost.

The method may also include decoding the acoustic signal received fromthe acoustic tag to identify and track the host in up to threedimensions in real-time or as a function of time.

The acoustic transmission device may be configured for tracking asturgeon host or another underwater host.

The foregoing summary is neither intended to define the invention of theapplication, which is measured by the claims, nor is it intended to belimiting as to the scope of the invention in any way.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an acoustic transmission device of the present inventionand associated length dimensions.

FIG. 2 is a block diagram showing components of the acoustictransmission device.

FIGS. 3A-3B are different top views of the present invention.

FIGS. 4A-4B are different bottom views of the present invention.

FIG. 5 shows a circuit diagram of the acoustic transmission device ofthe present invention.

DETAILED DESCRIPTION

A new acoustic transmission (tag) device and process are disclosed foridentification and remote tracking of various small hosts including,e.g., juvenile sturgeon, and other deep-water and underwater hosts in upto three dimensions (3D) (i.e., X-Y-Z coordinates). In the followingdescription, embodiments of the present invention are described by wayof illustration of the best mode contemplated for carrying out theinvention. Various components including, e.g., a transducer, tag anddrive circuitry, and a power source are described that address specificperformance requirements (e.g., size, mass, signal intensity, range, andtag lifetime). It will be apparent that the invention is amenable tovarious permutations, modifications, and alternative constructions. Itshould be understood that there is no intention to limit the presentinvention to specific forms disclosed herein, but, on the contrary, thepresent invention is to intended cover all modifications, alternativeconstructions, and equivalents falling within the scope of the presentinvention as defined in the claims. Therefore the description should beseen as illustrative and not limiting.

Acoustic tags of the present invention may include various form factorsand shapes that allow the tags to be attached to selected hosts forselected applications. However, shapes are not intended to be limited.The term “form factor” used herein refers to the physical arrangement,configuration, and dimensions of electrical components in the acoustictags and the capsule that contains the device components. The term“host” refers to inanimate or animate objects to which the acoustic tagmay be attached for tracking and/or identification. Inanimate hostsinclude, but are not limited to, e.g., propelled objects (e.g., robots),stationary objects, movable objects, and transportable objects. Animatehosts may include, but are not limited to, e.g., aquatic speciesincluding, e.g., marine and freshwater animals, deep water hosts (e.g.,juvenile sturgeon, lamprey, and eels), divers, underwater mammals, andother living hosts. The present invention will now be described withreference to tracking of an exemplary deep-water host, i.e., juvenilesturgeon. However, it should be understood that the invention is notintended to be limited thereto. As discussed above, acoustic tags of thepresent invention are well suited for a wide variety of applications andtracking of different hosts. No limitations are intended.

FIG. 1 is a perspective view of a new acoustic transmission device(acoustic tag) 100 of the present invention. In the exemplaryembodiment, acoustic tag 100 may include an elongated or cylindricalshape that permits the tag to be easily implanted in, or attached to,the selected host. Approaches for attachment are not limited. TABLE 1lists exemplary parameters of the new acoustic tag.

TABLE 1 Dimensions 24.2 mm × Ø5.0 mm* (Length × Diameter): Dry Weight:720 mg Volume: 429 mm³ Source Level: 159-163 dB (re: 1 μPa @ 1 meter)Tag lifetime: 98-156 days at 5-second pulse rate interval (163 dB and159 dB, respectively) Tag lifetime: 285-365 days at 15-second pulse rateinterval (163 dB and 161 dB, respectively) Transmission Range: Up to 500meters (163 dB) *Ø is an engineering unit for diameter, given here inmillimeters.

In the exemplary embodiment, tag 100 may include a length of 24.2 mm anda maximum diameter of 5.0 mm. The front end of the tag may include anarrower dimension than the back end of the tag and may include arelatively flat profile to minimize weight of the tag. The acoustic tagincludes a compact volume, and a mass of about 720 mg in air. Tag 100further includes a unique tag circuit that drives transmission of theacoustic signal from the PZT, a power source with a greater poweroutput, an enhanced and adjustable acoustic signal intensity (or sourcelevel), a selectable and longer tag lifetime, and a longer transmissionrange for tracking selected hosts. The acoustic transmission signal maybe adjusted to provide various detection ranges and tag lifetimes.

FIG. 2 is a block diagram showing exemplary components of acoustic tag100 of the present invention and associated electrical inputs andoutputs. Tag 100 may include a power source (e.g., battery) 10 thatpowers components of the acoustic tag. Power source 10 may be a customlithium carbon fluoride battery of a similar design to that described inU.S. application Ser. No. 14/014,035. Each laminate may include an anodeand a cathode positioned between polymer separators that electricallyisolate the cathode from the anode in the laminate. The separator mayinclude micro-porous polypropylene. The cathode may include, or beconstructed of, e.g., carbon fluoride and a conducting carbon within abinder affixed at a selected thickness to a current collector. Thebinder may include, e.g., polytetrafluoroethylene (PTFE). The anode maybe constructed of lithium metal. The power source may be filled with anelectrolyte such as, e.g., lithium hexafluorophosphate (LiPF₆) disbursedin a selected volume ratio of ethylene carbonate (EC) and dimethylcarbonate (DMC). In the exemplary embodiment, power source may be of alarger size that provides a greater power output of up to about 80 mAhand a longer tag lifetime. In the instant design, power source 10 mayinclude a plurality of laminates configured to supply a selectableoutput voltage between about 1.8 volts (1.8 V) to about 3.0 volts (3.0V).

Tag 100 may also include a programmable microcontroller 6 (U1) (e.g., amodel PIC16F1823T/CL 8-bit, 8K flash, programmable microcontroller in achip-scale package, Microchip Technology, Chandler, Ariz., USA) thatprovides operational control of components of acoustic tag 100. Tagcomponents are configured to generate and deliver an acoustic signal ata desired modulation or resonance frequency (e.g., 416.7 kHz) that istransmitted from the acoustic tag.

Resonator 28 (Y1) (e.g., a model CSTCE10M0G52-R0, 10 MHz ceramicresonator, Murata Manufacturing Co., Ltd., Nagaokakyo, Kyoto Prefecture,Japan) may be coupled on the input side of microcontroller 6 (U1) togenerate a clock signal of a selected precision (e.g., ±0.5% toleranceor better) that controls operation of controller (U1) 6 and othercomponents of acoustic tag 100.

A phototransistor (Q3) 26 (e.g., a model PT19-21B, flat black mini SMDphototransistor, Everlight Electronics Co., Ltd., New Taipei City,Taiwan) sensitive to optical or infrared radiation may be coupled on theinput side of microcontroller 6 to receive configuration commands froman external computer.

Tag 100 may further include a dual boost converter sub-circuit 36 thatcouples to two analog switches 40 (U2) and 42 (U3). Analog switch 42(U3) may be coupled to a high-efficiency resonance inductor 12 (L1)(e.g., a 10 uH, 80 MAmp, 20% tolerance inductor, Coilcraft, Cary, Ill.,USA). Analog switch 40 (U2) and resonance inductor 12 (L1) may becoupled to piezoelectric transducer 8. The dual boost convertersub-circuit, two analog switches, and resonance inductor togethergenerate a drive voltage that drives transmission of the acoustic signalfrom piezoelectric transducer 8 at a selected modulation or resonancefrequency, e.g., 416.7 kHz.

Dual boost converter sub-circuit 36 also controls the intensity of theacoustic signal delivered from piezoelectric transducer 8. The signalintensity is selectable between about 159 dB and about 163 dB. Selectionof the power source voltage and the acoustic signal intensity provides aselectable tag lifetime.

Components of tag 100 may be selected to reduce physical dimensions andweight of the tag, and may be coupled to both sides of a circuit board 2as shown in FIG. 3A and FIG. 4A described hereafter. Circuit board 2 maybe constructed of rigid board materials (˜0.02 cm thickness) such as FR4boards, or flexible board materials (˜0.01 cm thickness) such as flexboards.

FIGS. 3A-3B present different top-side views of circuit board 2 showingposition of selected components of acoustic tag 100. In these figures,piezoelectric transducer 8 is shown electrically coupled to circuitboard 2, e.g., at a forward end of acoustic tag 100 such that theacoustic signal may be transmitted free of interference from orobstruction by other tag components. Power source 10 may be coupled tocircuit board 2 at an end opposite piezoelectric transducer 8 to poweroperation of piezoelectric transducer 8 and other tag components.However, location is not intended to be limited.

Resonator 28 (Y1) (e.g., a 10 MHz ceramic resonator described previouslyin reference to FIG. 2) may be coupled to microcontroller 6 to controltiming of operation of tag components. Phototransistor 26 (Q3) may bepositioned to receive configuration commands from a source computer.Analog switches 40 (U2) and 42 (U3) may be positioned to deliver a drivevoltage to PZT 8 of about 20 volts (peak-to-peak) directly topiezoelectric transducer 8, or to deliver the same drive voltage acrossa resonance inductor 12 (L1) to piezoelectric transducer 8 as describedpreviously herein.

Tag 100 components may be encapsulated within a coating composed of athermosetting polymer such as an epoxy (e.g., EPO-TEK® 301 epoxy, EpoxyTechnology Inc., Bellerica, Mass., USA) or a resin (e.g., Scotchcast®Electrical Resin 5, 3M Company, St. Paul, Minn., USA) that forms acapsule 4.

In FIG. 3B, a resistor 30 (R1) (e.g., a 1.0 Mohm, 1/20 W, 5% tolerance,SMD resistor, Vishay Intertechnology, Inc., Malvern, Pa., USA) may becoupled in parallel with resonator 28 (Y1) to stabilize the frequency ofresonator 28 (Y1).

A bypass capacitor 20 (C3) (e.g., a model CL03A105MP3NSNC, 1-μF,10-volt, 20% tolerance, X5R dielectric, and 0201 size tantalumcapacitor, Samsung Electro-Mechanics America, Inc., Irvine, Calif., USA)may be coupled to controller 6 and power source 10 to filter electronicnoise and current spikes stemming from components on circuit board 2. Aswill be appreciated by those of ordinary skill in the art, electricalcomponents may be positioned where needed. No limitations are intended.

FIGS. 4A-4B are different bottom-side views of circuit board 2 showingposition of selected components of acoustic tag 100. Piezoelectrictransducer 8 and power source 10 may be coupled as described previously(see FIG. 3A-3B).

Microcontroller 6 (U1) may control operation of the components of thetag. In the exemplary embodiment, microcontroller 6 (U1) is shownpositioned adjacent piezoelectric transducer 8, but position is notintended to be limited thereto.

A first transistor 22 (Q1) (e.g., a model PMZB350UPE-315, 20-volt,p-channel MOSFET, NXP Semiconductors, San Jose, Calif., USA), a firstcapacitor 16 (C1) (e.g., a 47 uF, 10-volt, 20% tolerance, X5Rdielectric, and 0805 size ceramic capacitor, TDK Corp., Minato, Tokyo,JP), and an inductor 14 (L2) (e.g., a 10 uH, 80 MAmp, 20% tolerance, and0603 size inductor, TDK Corp., Minato, Tokyo, JP) are components of thedual boost converter sub-circuit 36. These components generate thenegative output voltage (e.g., about −3 volts), and couple electricallyto analog switches 40 (U2) and 42 (U3) described previously in referenceto FIG. 2 and FIGS. 3A-3B.

A second transistor 24 (Q2) (e.g., a 30-volt, 1.78 A, N-channel MOSFET,Fairchild Semiconductor, Inc., Dallas, Tex., USA) and a second capacitor18 (C2) (e.g., a 47 uF, 10-volt, 20% tolerance, X5R dielectric, and 0805size ceramic capacitor, TDK Corp., Minato, Tokyo, JP), are additionalcomponents of the dual boost converter sub-circuit 36. These componentsshare inductor 14 (L2) described previously above and together generatethe positive output voltage (e.g., about +7 volts), and coupleelectrically to analog switches 40 (U2) and 42 (U3) described previouslyin reference to FIG. 2 and FIGS. 3A-3B.

Analog switch 42 (U3) may couple to piezoelectric transducer 8 throughinductor 12 (L1) to increase the drive voltage across the piezoelectrictransducer.

In FIG. 4B, a first diode 32 (D1) (e.g., a 30-volt, 0.1 A, 2DFN SchottkyDiode 0201, Diodes, Inc., Plano, Tex., USA) and a second diode 34 (D2)(e.g., a 30-volt, 0.1 A, 2DFN Schottky Diode 0201, Diodes, Inc., Plano,Tex., USA) are additional components of the dual boost convertersub-circuit 36. First diode 32 (D1) assists in the generation of thenegative voltage (e.g., −3 volts), and second diode 34 (D2) assists inthe generation of the positive voltage (e.g., +7 volts).

Tag Circuit

FIG. 5 shows an exemplary tag circuit for acoustic tags of the presentinvention showing components described previously above. Components maybe located on, or coupled to, a circuit board described previously inreference to FIG. 2. The tag circuit may include preferred trace linewidths of about 0.01 cm (0.003 inches), but are not intended to belimited.

Configuration commands for programming microcontroller 6 may be receiveddirectly from an external computer (not shown), e.g., through anIntegrated Circuit Serial Programmer (ICSP) module 48 (e.g. a MPLAB ICD3 programmer, Microchip Technologies, Chandler, Ariz., USA) that couplesto microcontroller 6. Programmer (ICSP) module 48 may couple to theexternal computer through a programming connector (e.g., a model22-05-2061, 6-position connector, Molex Connector Corp., Lisle, Ill.,USA) (not shown). The programming connector may be detached from thecircuit board during assembly of the acoustic tag to reduce the finalvolume of the assembled tag.

Configuration and programming information may also be delivered remotely(e.g., optically) from the external computer through phototransistor 26(Q3) and into controller 6 through a selected input pin. Pins are notintended to be limited.

Bypass capacitor 20 (C3) may be coupled to controller 6 and power source10 to filter electronic noise and current spikes from components on thecircuit board.

Resonator 28 (Y1) delivers a clock signal that controls the timing ofdelivery of a positive channel drive signal (PCH-DRV) and a negativechannel drive signal (NCH-DRV) to dual boost converter sub-circuit 36described hereafter. A resistor 30 (R1) may be placed in parallel withresonator 28 (Y1) to stabilize the frequency and clock signal ofresonator 28 (Y1).

Dual boost converter sub-circuit 36 may include a first transistor 22(Q1), an inductor 14 (L2), a first diode 32 (D1), and a first capacitor16 (C1) that together generate a negative output voltage (e.g., −3volts). Microcontroller 6 may toggle the PCH-DRV signal to alternatelybuild up current through inductor 14 (L2), and then discharges capacitor16 (C1) through diode 32 (D1). Magnitude of the positive output voltagedepends in part on the length of time that microcontroller 6 toggles thePCH-DRV signal. Microcontroller 6 may hold the NCH-DRV signal at apositive voltage during operation so that a second transistor 24 (Q2)described hereafter can conduct current.

Dual boost converter sub-circuit 36 may include second transistor 24(Q2), inductor 14 (L2), second diode 34 (D2), and second capacitor 18(C2) that together generate a positive output voltage (e.g., +7 volts).Microcontroller 6 toggles the NCH-DRV signal to alternately build upcurrent through inductor 14 (L2), and then charge capacitor 18 (C2)through diode 34 (D1). The magnitude of the positive output voltagegenerally depends on the length of time that the microcontroller togglesthe NCH-DRV signal. Microcontroller 6 (U1) may hold the PCH-DRV signalat zero voltage during this operation so that first transistor 22 (Q1)can conduct current.

Dual boost converter sub-circuit 36 may couple to two analog switches 40(U2) and 42 (U3). The two analog switches respectively receive thepositive and negative output voltages from the dual boost convertersub-circuit 36. The analog switches switch between these two voltagesalternately in succession, under the control of microcontroller 6 (U1),to generate a selected (drive) voltage from the tag circuit that isdelivered to piezoelectric transducer 8. Analog switch 40 (U2) maycouple to one terminal (e.g., negative terminal) of piezoelectrictransducer 8. Analog switch 42 (U3) may couple through a resonanceinductor 12 (L1) to another terminal (e.g., positive terminal) ofpiezoelectric transducer 8. The drive voltage may be delivered fromanalog switch 42 (U3) through resonance inductor 12 (L1) topiezoelectric transducer 8 to generate the acoustic signal transmittedfrom piezoelectric transducer 8. Resonance inductor 12 (L1) isconfigured to increase the voltage delivered at the terminals ofpiezoelectric transducer 8. The acoustic signal transmitted frompiezoelectric transducer 8 may have a selected modulation frequency(e.g., 416.7 kHz). The value of inductor 12 (L1) may be selected suchthat the inductance partially or fully cancels out characteristiccapacitances of piezoelectric transducer 8 at the selected modulationfrequency. The resulting voltage at each terminal of piezoelectrictransducer 8 may go above the positive drive voltage and below thenegative drive voltage. As will be appreciated by those of ordinaryskill in the art, modulation frequencies may be varied and hence are notintended to be limited to the exemplary value described herein.

Tag Lifetimes

Lifetimes of acoustic tags of the present invention depend in part onthe size of the power source (battery) 10 described previously inreference to FIG. 5. However, for a given power source size, in general,tag lifetimes are selectable by selecting: 1) the PRI for transmissionof the acoustic signal, 2) the intensity of the acoustic signal, or 3)both the PRI and the intensity of the acoustic signal.

Within the selectable range of acoustic intensity between about 159 dBand about 163 dB, tag lifetimes may be estimated from empirical equation[1]:

$\begin{matrix}{T = {\frac{V_{batt}*C_{batt}*t_{0}*1000}{130 + {35*10^{\frac{{SL} - 155}{10}}} + {V_{batt}*I_{S}*t_{0}}}*\frac{1}{24}}} & \lbrack 1\rbrack\end{matrix}$

Here, lifetime (T) has units of days. (V_(batt)) is the battery voltageand has units of volts. (C_(batt)) is the battery capacity in units ofmilli-Amp-Hours (mAh). (SL) is the acoustic intensity (or source level)in units of dB. (I_(s)) is the constant static current that flowsthrough the tag circuit (FIG. 5) in units of micro-Amps. (t₀) is the PRIin units of seconds. TABLE 2 lists exemplary constants that may beemployed for calculating tag lifetimes (T) at a PRI (t₀) of 5 secondsand a signal strength (intensity) of 163 dB:

TABLE 2 Item Values V_(batt) 3.0 V C_(batt) 56 mAh SL 163 dB t₀ 5seconds I_(s) 0.4 μA

From Equation [1], tag lifetime (T) may be calculated at about 98 daysusing identified variable values. Acoustic tags of the present inventionare configured to maintain a selected energy expenditure (e_(pulse)) foreach transmission of the acoustic signal even as battery voltagedecreases gradually over time. Energy expenditure (e_(pulse)) values maybe less than or equal to about 385 μJ per transmission at a signalintensity of 163 dB, and less than or equal to about 283 μJ pertransmission at a signal intensity of 161 dB.

Actual tag lifetimes (T) may be longer than calculated lifetimes basedon nominal energy expenditure (e_(pulse)) values. As an example, at asignal intensity (strength) setting of 163 dB, an empirical energyconsumption value of 351 μJ per transmission may be used instead of thenominal 385 μJ for a more accurate estimate of tag lifetime. In anotherexample, at a signal strength setting of 161 dB, an empirical energyconsumption value of 269 μJ may be used instead of the nominal 283 μJ.

TABLE 3 lists experimental and projected tag lifetimes for acoustic tagsof the present invention at selected PRIs and selected signalintensities.

TABLE 3 PRI (t₀) (seconds) 0.5 1 5 10 15 Tag @163 dB 8.9 19.9 98 193 285Lifetime (T) @161 dB 12.9 25.9 127 249 365 (days) Note: ExperimentalProjected values values

Lifetimes (T) of acoustic tags of the present invention are selectable.Shorter tag lifetimes and longer tag lifetimes may be selected. In thetable, it can be seen that for a selected signal intensity, tag lifetimemay be selected by varying the PRI. For example, at a signal intensityof 163 dB, tag lifetime corresponding to a 5 sec PRI is about 98 days;tag lifetime corresponding to a 15 sec PRI is about 285 days. It will bereadily understood by those of ordinary skill in the art that varioussignal intensities may be selected with their corresponding lifetimes atselected PRIs to meet specific tracking needs for selected hosts and/orfor selected applications. No limitations are intended. For example, fora tag with a signal intensity set at 161 dB, tag lifetime may be atleast about 12.9 days using a PRI of 0.5 seconds, at least about 127days using a PRI of 5 seconds, or about 365 days using a PRI of 15seconds.

Beam Transmission Patterns

Beam transmission patterns of the piezoelectric transducer aredescribed, e.g., in U.S. application Ser. No. 14/014,035 filed 29 Aug.2013.

Transmission Detection Range

Acoustic signals transmitted by tags of the present invention mayinclude selected detection ranges. Tag signals may be encoded to providemaximum strength and to improve range and resolution. In locations witha relatively small amount of background noise, such as the middle of alake, signals may be transmitted up to about 500 meters. The present tagdelivers a higher source level output to provide for the 500-meterdetection range than used in previous tags. TABLE 4 lists projecteddetection ranges at two exemplary intensity values of 163 dB and 161 dBfor three different signal transmission spread scenarios and an assumednoise level of 97 dB in a quiet environment (e.g. the forebay of a dam).However, no limitations are intended by the illustrative example.

TABLE 4 Detection range (meters) Spherical Realistic* CylindricalForebay @163 dB 726 512 770 @161 dB 249 475 277 *A noise level of 97 dBis presumed based on actual noise level measurements.

Data suggest a transmission detection range of 500 meters or better maybe achieved at an acoustic signal intensity selected from 159 dB to 163dB. In locations with larger background noise (e.g., immediatelydownstream of a dam spillway), signals may be transmitted about 100meters. However, distances are not intended to be limited.

Coding and Activation

Tags of the present invention may be programmed with one or more tagcodes of a selectable code length. The microcontroller (FIG. 2) may alsocontain internal sensors such as temperature sensors that collectadditional data from the host and surrounding environment. As anexample, a 5-bit temperature value or other sensor values with selectedbit-lengths may be input from selected sensors into one or more tagcodes that are then transmitted from the piezoelectric transducer.Coding and sensors are described in U.S. application Ser. No. 14/014,035filed 29 Aug. 2013.

Methods and locations for attachment of acoustic tags to selected hostsare not limited. Acoustic tags may be attached, e.g., to the outside ofthe host (e.g., to the clothing or scuba gear of a human host), to aninanimate object, to a self-propelled object such as a robot, attachedinternally to the host (e.g., inserted within an object, surgicallyimplanted, or injected). No limitations are intended.

Applications for acoustic tags of the present invention may include, butare not limited to, e.g., survival studies; monitoringmigration/passage/trajectories; tracking host behavior or location intwo dimensions (2D) or three dimensions (3D); measuring bypasseffectiveness at dams and other passages; observing predator/preydynamics; helping public utility agencies, private firms, and state andfederal agencies meet fishery or other regulations; and otherapplications. Applications are not intended to be limited.

The present invention delivers unsurpassed advantages not obtained inprevious designs and open up a broad array of tag uses and applicationsnot yet realized. The high-efficiency piezoelectric transducer drivecircuit in the instant design enhances energy conversion efficiency andreduces number of dedicated components, all while maintaining the samesource level performance. Fewer components decreases the energy requiredto power the tag, which permits yet smaller acoustic tags with a lowermass to be constructed for even smaller hosts and applications.

While the invention has been described with what is presently consideredto be the most practical and preferred embodiments, many changes,modifications, and equivalent arrangements may be made without departingfrom the invention in its true scope and broader aspects. Thus, thescope is expected to be accorded the broadest interpretation relative tothe appended claims. The appended claims are therefore intended to coverall such changes, modifications, equivalent structures, and products asfall within the scope of the invention. No limitations are intended.

What is claimed is:
 1. An acoustic transmission (tag) device,comprising: a power source; a tag circuit; a piezoelectric transducer; ahousing configured to be associated with a host to be tracked andwherein the housing is coupled with the power source, the tag circuitand the piezoelectric transducer; and wherein the power source deliversa power source voltage to power the tag circuit, and the tag circuitdelivers a selected voltage to the piezoelectric transducer thattransmits an acoustic transmission signal at a selected signal intensitybetween about 159 dB and about 163 dB.
 2. The acoustic device of claim1, wherein the tag is configured to provide a tag lifetime of at leastabout 365 days at a pulse rate interval of about 15 seconds and a signalintensity of 161 dB.
 3. The acoustic device of claim 1, wherein the tagcircuit includes a dual boost converter sub-circuit that couples to twoanalog switches that deliver the selected voltage to the piezoelectrictransducer.
 4. The acoustic device of claim 1, wherein the tag circuitincludes a dual boost converter sub-circuit that generates voltagepotentials that alternate between about −3 volts and about +7 volts. 5.The acoustic device of claim 1, wherein the tag circuit delivers aselected voltage delivered to the piezoelectric transducer that is atleast about 20 volts (peak-to-peak).
 6. The acoustic device of claim 1,wherein the power source delivers a selectable power source voltagebetween about 1.8 V to about 3.0 V.
 7. The acoustic device of claim 1,wherein the tag circuit expends an energy for transmission of theacoustic signal from the piezoelectric transducer of less than or equalto about 283 μJ per transmission at a signal intensity of 161 dB.
 8. Theacoustic device of claim 1, wherein the tag circuit expends an energyfor transmission of the acoustic signal from the piezoelectrictransducer of less than or equal to about 385 μJ per transmission at asignal intensity of 163 dB.
 9. The acoustic device of claim 1, whereinthe piezoelectric transducer delivers the acoustic signal over atransmission range up to at least about 500 meters at full intensity.10. A method for tracking a selected host, comprising the steps of:associating an acoustic transmission (tag) device with a selected hostto be tracked; while the acoustic transmission (tag) device isassociated with the host, delivering a selected voltage from a tagcircuit powered by a power source to a piezoelectric transducer in theacoustic transmission (tag) device to generate an acoustic transmissionsignal therein; while the acoustic transmission (tag) device isassociated with the host, transmitting the acoustic transmission signalfrom the piezoelectric transducer at a selected signal intensity betweenabout 159 dB and about 163 dB to track the selected host; and while theacoustic transmission (tag) device is associated with the host,transmitting the acoustic transmission signal externally of the host.11. The method of claim 10, wherein transmitting the acoustictransmission signal includes a tag lifetime of at least about 365 daysat a pulse rate interval of about 15 seconds at a signal intensity of161 dB.
 12. The method of claim 10, wherein delivering the selectedvoltage from the tag circuit includes generating the voltage in a dualboost converter sub-circuit that couples to two analog switches withinthe tag circuit.
 13. The method of claim 10, wherein delivering theselected voltage from the tag circuit includes generating voltagepotentials in a dual boost converter sub-circuit that alternates betweenabout −3 volts and about +7 volts.
 14. The method of claim 10, whereindelivering the selected voltage from the tag circuit includes a voltageof at least about 20 volts (peak-to-peak).
 15. The method of claim 10,wherein delivering the selected voltage from the tag circuit includesdelivering a power source voltage from the power source selected betweenabout 1.8 V to about 3.0 V.
 16. The method of claim 10, whereintransmitting the acoustic signal includes an energy expenditure by thetag circuit of less than or equal to about 283 μJ per transmission at asignal intensity of 161 dB.
 17. The method of claim 10, whereintransmitting the acoustic signal includes an energy expenditure by thetag circuit of less than or equal to about 385 uJ per transmission at asignal intensity of 163 dB.
 18. An acoustic transmission (tag) device,comprising: a tag circuit comprising components that deliver aselectable voltage to a piezoelectric transducer that drivestransmission of an acoustic transmission signal therefrom at a selectedacoustic signal intensity; and a power source coupled to the tag circuitand which is configured to deliver a selectable power source voltagethat powers the components of the tag circuit over a selectable taglifetime of at least about 98 days at a pulse rate interval of about 5seconds at an acoustic signal intensity of 163 dB.
 19. The acousticdevice of claim 1, wherein the tag is configured to provide a selectabletag lifetime at the selected signal intensity of at least about 98 daysat a pulse rate interval of about 5 seconds.
 20. The method of claim 10,wherein transmitting the acoustic transmission signal includes a taglifetime of at least about 98 days at a pulse rate interval of about 5seconds.
 21. The acoustic device of claim 1, wherein the tag has avolume of about 429 mm³ or less.
 22. The acoustic device of claim 1,wherein the tag has a mass of about 720 mg or less in air.
 23. Theacoustic device of claim 1, wherein the tag circuit comprises: a dualboost converter configured to generate a negative output voltage and apositive output voltage; and an inductor configured to increase thevoltage which is delivered to the piezoelectric transducer.
 24. Theacoustic device of claim 23, further comprising: a first switch coupledwith the dual boost converter and a terminal of the piezoelectrictransducer; and a second switch coupled with the dual boost converterand the inductor.
 25. The acoustic device of claim 1, wherein thehousing is configured to be received within the host to be tracked. 26.The acoustic device of claim 1, wherein the tag circuit comprises: adual boost converter configured to generate a negative output voltageand a positive output voltage; and an inductor between the dual boostconverter and the piezoelectric transducer.
 27. The acoustic device ofclaim 26, further comprising: a first switch coupled with the dual boostconverter and a terminal of the piezoelectric transducer; and a secondswitch coupled with the dual boost converter and the inductor.